Research is proposed aimed at increasing our understanding of the nature of the genes determining protein structure in eukaryotes and the control of their expression. Three major systems are to be investigated for their own intrinsic interest and to permit further development and testing of Smithies' DNA-network hypothesis (1970). 1. Immunoglobulins: We will investigate the linkage relationship of the genes controlling Beta 2-microglobulin and immunoglobulin heavy and light chains. 2. Hemoglobins: We will obtain data on the distribution of the various mouse hemoglobin chains among single red cells. We will begin experiments in mice to determine whether the products of cis Beta- chain genes are coordinately synthesized. 3. Histones: We will determine whether histones segregate mitotically in a semiconservative fashion similar to DNA. Sequencing Radioactive Proteins: We will continue trying to develop methods for sequencing radioactive proteins.